WO1990010519A1

WO1990010519A1 - Laser output control system

Info

Publication number: WO1990010519A1
Application number: PCT/JP1990/000280
Authority: WO
Inventors: Takeji Arai
Original assignee: Fanuc Ltd
Priority date: 1989-03-09
Filing date: 1990-03-02
Publication date: 1990-09-20
Also published as: EP0419671A1; EP0419671A4; JPH02235588A

Abstract

A laser output control system for an NC laser in which a numerical control apparatus (CNC) and a gas laser oscillator are coupled together. There are provided a first output control mode and a second output control mode. In the first output control mode, a shutter is closed (S2) prior to starting the machining, and the laser is pre-oscillated to raise the temperature of a laser gas in order to maintain constant the temperature of the inner wall of the discharge tube (S3 to S6). When a machining instruction is input, the base discharge condition is once established (S8), the shutter is opened (S9), and the output instruction value is increased to produce laser beams. This makes it possible to realize the output control by taking advantages of a conventional shutter control system and a beam control system. In the second output control mode, the base discharge condition is established (S11) and the shutter is opened (S12) to effect the machining. The second output control mode is featured by energy saving, reduced heat generation and long life. This first and second output control modes can be selected by an operator depending upon the type of machining.

Description

Description Laser output control method Technical field

The present invention relates to a laser output control method of an NC laser device in which a numerical control device (CNC) is combined with a gas laser oscillator, and more particularly to a laser output control method capable of saving energy and obtaining high processing accuracy. Background technology

Laser output control methods are roughly classified into a so-called shutter control method and a beam control method. Conventional laser devices are provided with either control method depending on the application.

The shutter control method is a method of controlling the opening and closing of a shutter provided in the middle of the output path of laser light to the outside based on a processing command. Since the laser is emitted at a constant output before the start of machining and during machining interruption, the inner wall temperature of the discharge tube is always in a steady state. Therefore, the output mode of laser light is stable from the beginning of processing, and it is used especially for thin material processing where processing accuracy is important.

On the other hand, in the beam control method, when machining is not performed, the laser oscillator is in a base discharge state, and when a machining command is input, the output command value is increased and a laser is output. Therefore, compared to the shutter control method, it is energy saving type, generates less heat, and has a longer life of optical components. However, the advantages of each control system described above are disadvantageous in the other control systems.

That is, the shutter control method has a low operating efficiency and a short life of optical components. Also, the control performance is poor due to the slow opening and closing speed of the shutter.

On the other hand, the beam control method tends to be in a lower-order mode because the temperature of the inner wall of the discharge tube is low at the beginning of machining, and machining accuracy during this period decreases. Disclosure of the invention

The present invention has been made in view of such a point, and an object of the present invention is to provide a laser output control method which is energy saving and can obtain high processing accuracy.

In the present invention, in order to solve the above problems,

A first output control mode and a second output control mode are provided in a laser output control method of an NC laser device in which a numerical controller (CNC) and a gas laser oscillator are combined. In the first output control mode, machining is performed. Before starting, shut off the laser output path to the outside, pre-oscillate the laser, detect the laser gas temperature with the temperature detector and compare it with the set temperature.Laser output so that the laser gas temperature rises to the set temperature Controlling the laser gas temperature to maintain the inner wall temperature of the discharge tube in a steady state, and after inputting a machining command, turning on the base discharge state, opening the laser output path, and The laser oscillates at a predetermined output commanded by the above, and in the second output control mode, The laser output path is not interrupted, the preliminary oscillation, and the temperature control are not performed, and after a processing command is input, a base discharge state is established, the laser output path is opened, and a laser is output at a predetermined output commanded by the processing command. And a laser output control method characterized by switching between the first output control mode and the second output control mode according to a command.

In the first output control mode, the laser gas temperature is raised by pre-oscillating the laser with the shutter closed before machining starts to maintain the inner wall temperature of the discharge tube in a steady state. When a machining command is input, the system is once set to the base discharge state, then the shutter is opened and the output command value is increased to output the laser. This enables output control that takes advantage of both the conventional shutter control method and beam control method.

The second output control mode is equivalent to the conventional beam control method, and provides energy saving, low heat generation, and long life output control.

The first and second output control modes can be arbitrarily selected by the operator. BRIEF DESCRIPTION OF THE FIGURES FIGS. 1 (a) and 1 (b) are flow charts of a laser output control system according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a hard disk of an NC laser device for carrying out the present invention,

FIG. 3 is an example of a timing chart of each instruction when the Α mode is selected in one embodiment of the present invention. FIG. 4 is an example of a time chart of each command when the B mode is selected in one embodiment of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 2 is a block diagram showing a configuration of a hardware of an NC laser device for implementing the laser output control method of the present invention. In the figure, a processor 1 controls the operation of the entire NC laser device based on a machining command of a machining program (not shown). The output control circuit 2 has a built-in DZA converter and converts the output command PC output from the processor 1 into a current command value and outputs it. After rectifying the commercial power supply, the laser power supply 3 performs a switching operation to generate a high-frequency voltage, and supplies a high-frequency current corresponding to the current command value to the discharge tube 4.

A laser gas 19 is circulated inside the discharge tube 4, and when a high-frequency current is supplied from the laser power supply 3, a discharge occurs to excite the laser gas 19. The rear mirror 5 is a mirror made of germanium (Ge) with a reflectivity of 99.5%, and the output mirror 6 is a mirror made of zinc selenium (ZnSe) with a reflectivity of 40 to 55%. A Fabry-Perot resonator is configured to amplify the 10.6 um light emitted from the excited laser gas molecules and output a part of the light as laser light 7 from the output mirror 6 to the outside.

The output laser beam 方向 changes its direction by a vendor mirror 8 when a shutter 23 a described later is open, and is condensed by a condensing lens 9 to a spot of 0.2 mm or less, and a work 17 The surface is irradiated.

Memory 10 is a memory for storing machining programs and various parameters, and uses a battery backed-up CMOS or the like. The position control circuit 11 decodes the feed command CC output from the processor 1, controls the rotation of the servo motor 13 via the servo amplifier 12, and controls the table 1 by the ball screw 14 and the nut 15. The movement of 6 is controlled and the position of work 17 is controlled. In the figure, only one axis is shown, and the other axes are omitted. For the display device 18, a CRT or a liquid crystal display device is used. A parameter setting screen or a laser condition setting screen is displayed on this display screen. When an operator operates an operation key (not shown), one of two output control modes described later is interactively operated. You can select by format.

Roots blower or the like is used for blower 20 and laser gas 1

9 is circulated through coolers 21a and 21b. The cooler 21a is a cooler for cooling the laser gas 19 which has become high temperature by performing laser oscillation, and the cooler 21b is a cooler for removing heat of compression by the blower 20. .

The shutter control circuit 22 opens and closes the shutter 23 a based on the shutter opening and closing command SC output from the processor 1. The shutter 23a is made of a copper plate or an aluminum plate having a gold-plated surface, and when closed, reflects the laser light 7 output from the output mirror 6 and closes the beam absorber 2a. Absorb to 3b. When the shutter 23a is opened, the work 17 is irradiated with the laser beam 7. The power sensor 24 is composed of a thermoelectric or photoelectric conversion element or the like, inputs a laser beam transmitted through a part of the rear mirror 5, and measures the output power of the laser beam 7. A radiation thermometer is used for the temperature sensor 25, and measures the temperature of the laser gas 19 <The temperature of the laser gas 19 is measured to estimate the inner wall temperature of the discharge tube 4. The switch 26 switches between the output of the power sensor 24 and the output of the temperature sensor 2.5 according to a command from the processor 1. The AZD converter 27 converts the output of the switch 26 into a digital value and inputs it to the processor 1.

Next, a laser output control system according to an embodiment of the present invention will be described with reference to the flowcharts of FIGS. 1 (a) and 1 (b). In the figure, the number following S indicates the step number. In this embodiment, two output control systems, A mode and B mode, are provided. [S1] It is determined whether or not the A mode is selected. If the A mode is selected, the process proceeds to S2. If the A mode is not selected, the process proceeds to S10. C S 2] With the shutter open / close command S C kept off, output the output command PC and perform pre-oscillation.

[S3] The switch 26 is switched to the temperature sensor 25 side to measure the temperature of the laser gas 19, and the difference from the preset temperature is obtained to obtain the deviation temperature.

C S 4 J Judge whether the absolute value of the deviation temperature is smaller than the specified zero width.If smaller, go to S7.If not smaller, go to S5.

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[S5] Multiply the deviation temperature by a specific constant and calculate the deviation amount converted to the laser output value. [S6] Command the value obtained by adding the deviation to the current output command value as the output command PC, and go to S3.

[S7] Determine whether the machining command MC has been output. If it has been output, return to S8. If not, return to S3 and continue temperature control.

[S8] Set the output command value to 0 to set the base discharge state. At the same time, switch 26 is switched to the side of power sensor 24.

[S9] Output the shutter open / close command SC and open the shutter 23a.

[S10] It is determined whether or not the B mode is selected, and if it is selected, the process returns to S11. If not, the process returns to S1.

[S11] Set the output command value to 0 to set the base discharge state. At the same time, switch 26 is switched to the side of power sensor 24. [S1 2] Outputs shutter open / close command SC and opens shutter 2 3a.

[S13] Determine whether the machining command MC has been output. If it has been output, go to S14. If not, wait.

[S14] Output command PC and feed command CC are output based on machining command MC, and execute machining.

[S15] Finish machining, set the output command value to 0, and change to the base discharge state.

[S16] Shutdown shutter release command SC is turned off and shutter 23a is closed o

CS 17] Judge whether to end the operation, return to S18 if it is to end, return to S1 if not. [S18] Output command PC is turned off to stop discharging, and then cut off.

FIG. 3 is an example of a time chart of each command when the A mode is selected in the above embodiment.

After the operation is started, the output command PC commands a predetermined output value. However, as the temperature of the laser gas 19 increases, the output command value decreases and becomes a constant value p 0.

When the machining command MC commands "G24J (piercing)", the output command PC commands the base discharge, and the shutter opening / closing command SC is output. When the shutter 23a is opened, the output command PC is set. A predetermined output command value issued by the machining command MC is output, and the laser beam 7 is irradiated on the peak 1. When the piercing is completed, the shutter opening / closing command SC is turned off, and the output command PC is reset again. Command discharge.

When the machining command MC commands “G 0 1” (cutting), the output command PC once again commands the base discharge, and the shutter opening / closing command SC is output. When the shutter 23a is opened, the output command PC and the feed command CC output predetermined command values based on the machining command MC, respectively, so that the workpiece 17 is cut. At this time, the laser output is detected by the power sensor 24 and feedback is performed so that the laser output is controlled to match the output command value. When the cutting is completed, the shutter opening / closing command SC is turned off, and the output command PC commands the base discharge again.

Fig. 4 shows an example of the time chart of each command when B mode is selected. After the start of operation, the output command PC issues a base discharge command, the shutter opening / closing command SC is output, and the shutter 23a opens. When the machining command MC commands “G24” (piercing), the output command PC outputs a predetermined output command value, and the work 17 is irradiated with the laser beam 7. When the piercing is completed, the output command FC commands the base discharge again.

When the machining command MC instructs “G01J (cutting process)”, the work 17 is cut by the output command PC and the feed command CC outputting predetermined command values, respectively. The cutting is completed. And output command PC commands base discharge again.

As described above, in the present invention, the first output control mode and the second output control mode that can be arbitrarily switched are provided, and in the first output control mode, the shutter is closed before starting the machining. Preliminary oscillation of the laser raises the laser gas temperature to maintain the inner wall temperature of the discharge tube in a steady state.When a machining command is input, the system once returns to the base discharge state, then opens the shutter and increases the output command value. Since the laser is output, stable single-mode laser light can be output from the beginning of processing, and energy saving can be achieved compared to the conventional shutter control method and higher processing accuracy can be realized than the beam control method. .

In addition, the second output control mode has more energy saving, lower heat generation, and longer life than the first output control mode, and is advantageous when processing accuracy is not so important.

Furthermore, the first and second output control modes can be switched interactively with reference to the display screen of the NC laser device. It has good operability and can easily handle various types of machining.

Claims

The scope of the claims '

1. In the laser output control method of the NC laser device in which the numerical controller (CNC) and the gas laser oscillator are combined,

A first output control mode and a second output control mode are provided.In the first output control mode, a laser output path to the outside is cut off before processing is started, a laser is preliminarily oscillated, and a temperature is detected. The temperature of the inner wall of the discharge tube is stabilized by detecting the laser gas temperature with a heater, comparing the temperature with the set temperature, controlling the laser output so that the laser gas temperature rises to the set temperature, and controlling the temperature of the laser gas temperature. After the processing command is input, the laser output path is opened, the laser output path is opened, and the laser oscillates at a predetermined output commanded by the processing command.

In the second output control mode, the laser output path is not shut off, the preliminary oscillation and the temperature control are not performed, and after inputting a processing command, the laser output path is set to a base discharge state, the laser output path is opened, and the processing is performed. A laser output control method comprising: oscillating a laser at a predetermined output instructed by a command; and switching between the first output control mode and the second output control mode according to the command.

2. The laser output control method according to claim 1, wherein the switching of the output control mode is performed interactively with reference to a display screen of the NC laser device.

3. In the first output control mode, a patent is provided in which after the machining command is executed, a base discharge state is set, the laser output path is cut off, the preliminary oscillation is performed, and the temperature control is performed. The laser output control method according to claim 1.